1. Field of the Invention
The present invention relates to a vehicular brake apparatus which brakes a vehicle with wheel braking force generated by, for example, a control valve or a pump.
2. Related Arts
Conventionally, traction control (TRC) to decrease acceleration slip of a wheel or the like is well known as braking control performed when a driver does not depress a brake pedal, that is, during a no braking-operation of the driver. When this kind of braking control is executed, brake fluid pressure is provided to a wheel cylinder by a brake fluid circuit. For example, the brake fluid circuit has a master-cylinder cut-off (SMC) valve which can cut off the connection between the master cylinder and the wheel cylinder. The brake fluid circuit provides brake fluid pressure to the wheel cylinder by supplying pressurized brake fluid between the SMC valve and the wheel cylinder. That is to say, the SMC valve separates the wheel cylinder from the master cylinder. In this state, a pump generates the pressurized brake fluid which is supplied to the wheel cylinder. As a result, the brake fluid pressure in the wheel cylinder increases and a differential pressure is established between the two sides of the SMC valve.
In the system for performing traction control (or a system for performing anti-skid brake control (ABS)), a primary check therefor is normally executed. In this primary check, conductive states to each of valves or the pump are examined. In other words, the system checks whether cutoffs or short-circuits in electrical systems for each of the valves or the pump have occurred.
However, the system has no function for checking whether the differential pressure can be actually established between the two sides of the SMC valve or whether the pump can actually generate the pressurized brake fluid. Therefore, it is uncertain if the SMC valve and the pump work in the right way and the necessary brake fluid pressure can be supplied to the wheel cylinder. If the SMC valve or the pump functions insufficiently, an obstacle to braking control performed by the system may occur.